From bed062bbbe5b4cbcd9865f0915b41548e9c36c5c Mon Sep 17 00:00:00 2001
From: ti-srebot <66930949+ti-srebot@users.noreply.github.com>
Date: Fri, 15 Apr 2022 19:28:36 +0800
Subject: [PATCH] planner: fix wrong range calculation for Nulleq function on
 Enum values (#32440) (#32494)

close pingcap/tidb#32428
---
 planner/core/integration_test.go | 22 ++++++++++++++++++++++
 util/ranger/points.go            |  6 +++++-
 2 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/planner/core/integration_test.go b/planner/core/integration_test.go
index f6f2fd997d0fc..abf70803b9534 100644
--- a/planner/core/integration_test.go
+++ b/planner/core/integration_test.go
@@ -3231,6 +3231,28 @@ func (s *testIntegrationSuite) TestIssue26719(c *C) {
 	tk.MustExec(`rollback`)
 }
 
+func (s *testIntegrationSuite) TestIssue32428(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table `t1` (`a` enum('aa') DEFAULT NULL, KEY `k` (`a`))")
+	tk.MustExec("insert into t1 values('aa')")
+	tk.MustExec("insert into t1 values(null)")
+	tk.MustQuery("select a from t1 where a<=>'aa'").Check(testkit.Rows("aa"))
+	tk.MustQuery("select a from t1 where a<=>null").Check(testkit.Rows("<nil>"))
+
+	tk.MustExec(`CREATE TABLE IDT_MULTI15860STROBJSTROBJ (
+	  COL1 enum('aa') DEFAULT NULL,
+	  COL2 int(41) DEFAULT NULL,
+	  COL3 year(4) DEFAULT NULL,
+	  KEY U_M_COL4 (COL1,COL2),
+	  KEY U_M_COL5 (COL3,COL2))`)
+	tk.MustExec(`insert into IDT_MULTI15860STROBJSTROBJ  values("aa", 1013610488, 1982)`)
+	tk.MustQuery(`SELECT * FROM IDT_MULTI15860STROBJSTROBJ t1 RIGHT JOIN IDT_MULTI15860STROBJSTROBJ t2 ON t1.col1 <=> t2.col1 where t1.col1 is null and t2.col1 = "aa"`).Check(testkit.Rows()) // empty result
+	tk.MustExec(`prepare stmt from "SELECT * FROM IDT_MULTI15860STROBJSTROBJ t1 RIGHT JOIN IDT_MULTI15860STROBJSTROBJ t2 ON t1.col1 <=> t2.col1 where t1.col1 is null and t2.col1 = ?"`)
+	tk.MustExec(`set @a="aa"`)
+	tk.MustQuery(`execute stmt using @a`).Check(testkit.Rows()) // empty result
+}
+
 func (s *testIntegrationSerialSuite) TestPushDownProjectionForTiFlash(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("use test")
diff --git a/util/ranger/points.go b/util/ranger/points.go
index d60988ae722d7..5e75aac1efd59 100644
--- a/util/ranger/points.go
+++ b/util/ranger/points.go
@@ -456,6 +456,10 @@ func handleEnumFromBinOp(sc *stmtctx.StatementContext, ft *types.FieldType, val
 		res = append(res, &point{value: d, excl: false, start: false})
 	}
 
+	if op == ast.NullEQ && val.IsNull() {
+		res = append(res, &point{start: true}, &point{}) // null point
+	}
+
 	tmpEnum := types.Enum{}
 	for i := 0; i <= len(ft.Elems); i++ {
 		if i == 0 {
@@ -484,7 +488,7 @@ func handleEnumFromBinOp(sc *stmtctx.StatementContext, ft *types.FieldType, val
 				if v >= 0 {
 					appendPointFunc(d)
 				}
-			case ast.EQ:
+			case ast.EQ, ast.NullEQ:
 				if v == 0 {
 					appendPointFunc(d)
 				}